Rolling-balls grinding-mill.



L. HOPFMANN. ROLLING BALLS GRINDING MILL.

APPLICATION FILED JUNE 10, 1910.

Patented Nov. 15, 1910.

6 .lal'l' I I l I I nnw m 4 r w MM .mJVI 1 tears Hartman, victim, Atfs'rRiA-HUNGARY.

- ROLLING-Bans GRINDINFr-MILL.

Specification of Letters Patent.

Patented Nov. 15, 1910.

Application filed June 10, 1910. Serial No. 56,171. 1

To all whom it may concern:

Be it known that I, LoUIs HoFFMANN, a subject of the Emperor of Austria-Hungary, residing at Vienna, Empire of Austria-Hungary, have invented certain new and useful Im rovements in Rolling-Balls Grinding Mi s; and I do hereby declare the following to. be a full,-clear, and exact description of the invention, such as will enable others skilled in'the art to which it appertains to make and use the same. I v

My invention relates to rolling balls grinding mills having a revolving ball dish and a stationary grinding surface.

According to my invention the top side of the ball dish resembles generally speaking the shape of one, two or more sectors of coaxial helical surfaces, the axis of revolution of the ball dish being the common axis of the said sectors. Above this ball dish and adjacent thereto beating wings are provided on the shaft of the ball dish. Owing to this arrangement, the material fed to the mill as also those articles of the material being ground whlch are not yet sufliciently fine, come on falling down into the path of the beating wings and are disintegrated by them and thrown downward against the ball dish.

Onthe other hand the balls coming on. the ball dish are thrown not only outward, but

' also upward against the stationary grinding surface, and on striking against the latter and a ainst each other they bring about a very e cient and fine disintegrationor comminution of the material which they en: counter. i In the annexed drawings I have shown by way of example a preferred construction of a mill embodying my invention.

Figure 1 is a vertical section oi the same,

' some parts being shown in side elevation,

Fi' 2 is. afront elevationof the ball dish an beating wings; and Fig. 3 is a plan of Fig.2.

1 is the stationary rinding surface, preferably spherical in. grape and constituting the casing of the mill.

2 is a shaft extending through the casing and suitably journaled' in the same. This shaft is driven from the outside. and carries inside the casing the ball dish 3, and above the latter the beatin wings 4. The top side edges 5 of which-are in plan view in the form of arcsof spirals. The rear sldes of the sectors (as counted in the direction of revolution of the ball dish) rapidly fall 'down toward the base of-the ball dish, that The beating wings 4 are preferably provided with inclines 6 which are inclined relatively to the axisin the same direction as the sectors of the helical surfaces. The

lower art of the beating wings is preferably p ane and radial to the axis. 7

The bottom of the ball dish fits as closely as possible the adfiacent part of the grinding surface without coming into actual contact therewith. Air under pressure is blown in the well known manner through the space between the bottom side of the ball dish and the grinding surface, such air bein supplied from a suitable source to channe s leading tothe inside of the casing and ending in close proximity to the shaft 2 be low the ball dish. 1 The air under pressure thus escapes between the balldish and the inside of the casing andthus prevents any choking of the space between the two. I The upper part of the grinding surface is provided as ,usual with grates 7 on which sieves establish communication with a chamber 9'- in which the ground material is collected and from which it is removed by a tube 10. The current of air passing between the 'ball dish and the casing carrles the ground material toward .the sieves or bolting cloth 8, through which the material sufficiently finely comminuted escapes into the chamber 9, while the coarser particles fall back. into the grinding chamber. nThe material to be ground is introduced through the hopper 1.1 Into the grinding chamber in the well known sluice fashion manner, in order to prevent airfunder pressure from escaping through the .hopper 11. That is to say there are rovided two parallel slidin gates 12, 13 in t e chan- ,The operationof my improved mill is the described following: The material introduced is on falling down first encountered by the beating wings and thus broken and thrown against the stationary grinding surface. By the action of-the helical surfaces on the upper side of the revolving ball dish, the balls are not only thrown outward (owing to centrifugal force) but also upward and strike against each other and against the stationary grinding surface, thus comminuting very ethciently the material which they encounter and, then fall again on the ball dish and so on.

It willbe seen that the mill hereinbefore operates continuously, rapidly and efiiciently. 1

Claims: v

1. In arolling balls grinding mill the combination of a plurality of loose balls, a ball dish, a stationary grinding surface inclosing the ball dish and balls, means comprising a shaft for revolving the ball dish, the to side of the said ball dish being forme of a lurality of sectors of helical surfaces co-axial with the said shaft and the bottom of the ball dish conforming to the shape of the grinding chamber, said dish being slightly raised to form a space between the same and the wall of the rinding chamher and means for forcing air through said space, beating wings secured to the saidshaft above the ball dish, a collectin chamber fast on the grinding surface an means for sifting, establishing communication begrinding chamber, said dish being slightly raised to form a space between the same and the wall of the grinding chamber and means for forcing air through said space, beating -wings secured to the said shaft above the ball dish, each'of such beating wings being provided with apart inclined to the said shaft in the same direction as the sectors of the helical surfaces and with a plane part radial to such shaft, a collecting chamber fast on the grinding surface and means for sifting, establishing communication between the inside of the grinding surface and the'said collecting chamber, substantially as and for the purpose described.

In testimony whereof, I aflix my signature, in presence of two witnesses.

LOUIS HOFFMANN.

Witnesses ARTHUR BAUMANN, Aneos'r FUGGER. 

